(602f) Computational Studies of Free Energy Calculations of Cello-Oligosaccharide Adsorption On a Cellulose Crystal Surface

Enzymatic hydrolysis of cellulosic substrates is the key step in the production of biofuels when the biochemical platform is employed. During the hydrolysis process, the intermediate products (cello-oligosaccharides) which are formed due to the action of cellulases are known to adsorb onto the cellulosic surfaces, thus hindering further progress of the hydrolysis reaction. The goal of this work is to quantify the energetics of the process of separation of cello-oligosaccharides from cellulose substrates as well as to decipher the molecular mechanisms underlying this process. To this end, we have used umbrella sampling simulations to determine the free energy required for separating the smallest repeating units of cellulose and hemicellulose. Specific systems studied consisted of a cellobiose pair, a xylobiose pair and a pair of cellobiose and xylobiose molecules. These results will be compared with the free energy profile for the separation of a decamer of glucose from the cellulose crystal surface. In addition, results will also be presented for the dynamics of a cello-oligosaccharide molecule on the cellulose surface.